Hi Al,
I put 'suppressed' between '', there is (should be) no suppressed carrier as the whole signal is build digitally. There in no use to synthesize a carrier that is not needed. The IQ signal is needed to get rid of the mirror image signal due to the low IF of 11 kHz. Leakage can only be the local oscillator signal, but that is on about 11 kHz distance of the SSB signal (not exactly as the DDS local oscillator makes steps of a few kHz) It must be possible to hear the difference with a SSB receiver, 11 kHz is 3 times SSB bandwidth. I hope this explanation is clear enough (I am not a good writer and not a native speaker, I do my best, with help from the spell checker) I have spectrum analyzers, but my SDR1k is in parts at this moment, waiting for a bigger case. maybe one other member of this community can make some measurements. I am very interested to know what is really happening. groeten Peter petervn(a)hetnet.nl <mailto:[EMAIL PROTECTED]> ; pa0pvn(a)hetnet.nl <mailto:[EMAIL PROTECTED]> ; pa0pvn(a)gmail.com ; pa0pvn(a)amsat.org . ________________________________ Van: WARD,AL [mailto:[EMAIL PROTECTED] Verzonden: zo 4-2-2007 21:27 Aan: [EMAIL PROTECTED]; Frank Mayer; Ross; FlexRadio@flex-radio.biz Onderwerp: RE: [Flexradio] Residual carrier was SB question Peter What you say makes sense but I do hear the "suppressed" carrier. Maybe it is leakage. More tests on a spectrum analyzer with better freq resolution. Then I will disconnect the transmit cables from the Firebox and then the receive cables. Later Thanks 73 Al W5LUA ________________________________ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Sunday, February 04, 2007 1:34 PM To: Frank Mayer; WARD,AL; Ross; FlexRadio@flex-radio.biz Subject: RE: [Flexradio] Residual carrier was SB question Hi Ross, Let me think, No audio card connected to the transmitter mixer. In that case the signal you see will be the local oscillator. Must be about 11 kHz away from the SSB signal. On SSB transmission the local oscillator signal will be mixed with an 11kHz IQ (SSB) signal. This gives 2 resulting signals, on fo + 11 kHz and fo - 11 kHz. One of them is eliminated (almost) by the IQ 90 degrees phase trick. (the mirror image) If the carrier you see is the local oscillator signal then there is leakage from this signal. I do not know how good this must be isolated. Can not measure it SDR100o is in parts now, waiting for a bigger case. I can not see how a carrier on the SSB frequency can be generated, this signal should not have been in the IQ signal. Is the carrier the local oscillator or the 'suppressed carrier' belonging to the SSB signal ?? Suppressed SSB sig. -- Local oscillator -- SSB signal -11 kHz fo +11 kHz | | | virtual SSB cariers | 73 peter groeten Peter petervn(a)hetnet.nl <mailto:[EMAIL PROTECTED]> ; pa0pvn(a)hetnet.nl <mailto:[EMAIL PROTECTED]> ; pa0pvn(a)gmail.com ; pa0pvn(a)amsat.org . ________________________________ Van: Frank Mayer [mailto:[EMAIL PROTECTED] Verzonden: zo 4-2-2007 16:37 Aan: WARD,AL; [EMAIL PROTECTED]; Ross; FlexRadio@flex-radio.biz Onderwerp: Re: [Flexradio] Residual carrier was SB question I have no measurable noise from my D44 card. ----- Original Message ----- From: WARD,AL <mailto:[EMAIL PROTECTED]> To: [EMAIL PROTECTED] ; Ross <mailto:[EMAIL PROTECTED]> ; FlexRadio@flex-radio.biz Sent: Sunday, February 04, 2007 10:15 AM Subject: Re: [Flexradio] Residual carrier was SB question Peter When I disconnect the I and Q input to the SDR from the Firebox, the carrier is still there at about -50dBC. When the Firebox is connected to the radio, there is this noise modulating the carrier which ultimately brings it up to about -42 dBc. When modulating on SSB, the audio talks it up to the full power of the 1 watt radio. On CW a 600 Hz tone is injected to generate the CW 600 Hz offset from the carrier which is the "zero beat" on SSB. I wish there were a carrier null "pot" to push the carrier down even further like the old days on my Drake T4XB. I am considering some attenuation on the IQ lines feeding the radio in hopes of reducing the noise output from the Firebox and then possibly turning up the audio drive. Basically I trying to improve the S/N output from the Firebox which may not be possible. I would be interested to know if the D44 generates similar noise and how the new Firewire box performs. Just my thoughts. My biggest concern is that whenever I key up on cw like between characters (and I do not operate breakin) that I am transmitting this carrier with noise wrapped around it which is only -42 dBc. And when you reduce the drive on the front panel to lower power output to drive transverters the residual noise does not change. So in other words as the RF output is reduced my S/N when transmitting gets worse. The Radio Shack isolator/transformer does not help my situation. However I do use the SDR-1000 with WSJT and the VCOM and VAC and it works great on 1296 EME running JT-65C. I still like the radio Best Regards Al W5LUA EM13qc -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Sunday, February 04, 2007 4:04 AM To: Ross; FlexRadio@flex-radio.biz Subject: Re: [Flexradio] Residual carrier was SB question Thinking aloud, What is happening with the IQ cables disconnected? And what with the IQ inputs shorted? This to eliminate the soundcard and see if there is still a carrier. The other side, what signals are coming out of the soundcard when no mike or other input (in the transmit mode) Is there a signal of about 11 kHz ?? Or is there signal near 0 Hz ?? 73 peter pa0pvn groeten Peter petervn(a)hetnet.nl <mailto:[EMAIL PROTECTED]> ; pa0pvn(a)hetnet.nl <mailto:[EMAIL PROTECTED]> ; pa0pvn(a)gmail.com ; pa0pvn(a)amsat.org . ________________________________ Van: [EMAIL PROTECTED] namens Ross Verzonden: zo 4-2-2007 8:31 Aan: FlexRadio@flex-radio.biz Onderwerp: [Flexradio] Residual carrier was SB question I it is residual carrier, then we have a problem, I notice the same hum on digital mode, with just mox on, checking with my Orion II (on HF) and an FT736 (on VHF). That is from 2 different sound cards a Presonus firebox and the Ediroll. Can soemone please explain why this is happening and what I would do to remove the carrier. 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